Effective Potential Of Composite Fields Research Articles

Fractal structure of the effective action in (quasi)planar models with long-range interactions

We derive the effective potential for composite fields in a class of (quasi)planar models with long-range interactions. This class of models can be relevant for high temperature superconductors and graphite. The fractal structure of the effective potential is revealed and its physical interpretation is presented. It is argued that the multi-branched fractal structure of the potential reflects the presence of an infinite tower of excitonic bound states that occur as a result of the long-range interactions.

Effective potential of composite fields in weakly coupled QED in a uniform external magnetic field

The effective potential for the composite fields responsible for chiral symmetry breaking in weakly coupled QED in a magnetic field is derived. The global minimum of the effective potential is found to acquire a non-vanishing expectation value of the composite fields that leads to generating the dynamical fermion mass by an external magnetic field. The results are compared with those for the Nambu--Jona-Lasinio model.

Effective potential of composite fields in weakly coupled QED in a uniform external magnetic field

Effective potential of composite fields in weakly coupled QED in a uniform external magnetic field

NAMBU–JONA–LASINIO MODEL IN CURVED SPACETIME WITH MAGNETIC FIELD

We discuss the phase structure of the NJL model in curved spacetime with magnetic field using 1/N-expansion and linear curvature approximation. The effective potential for composite fields [Formula: see text] is calculated using the proper-time cutoff in the following cases: (a) at nonzero curvature, (b) at nonzero curvature and nonzero magnetic field, and (c) at nonzero curvature and nonzero covariantly constant gauge field. Chiral symmetry breaking is studied numerically. We show that the gravitational field may compensate the effect of the magnetic field what leads to restoration of chiral symmetry.

Restoration of dynamically broken chiral symmetry by a toroidal space-time.

The phase structure of the Nambu--Jona-Lasinio model with [ital N]-component fermions is investigated, in a toroidal ([ital S][sup 1][times][ital S][sup 1][times][ital R][sup 2]) space-time, in the leading order of the 1/[ital N] expansion. Examining the effective potential for composite fields, we find that the dynamically broken chiral symmetry may be restored below certain critical lengths of the toroidal dimension [ital l][sub 1],[ital l][sub 2]. We then derive critical-line equations in terms of the parameters of the model and the sizes of the toroidal dimension.

Schwinger-Dyson equations and effective potential for composite fields in quantum electrodynamics in curved spacetime

The effective potential (EP) for composite fields in quantum electrodynamics in curved spacetime is investigated. This EP is calculated to the accuracy of linear curvature terms. In the same approximation the Schwinger-Dyson (SD) equations in curved spacetime are obtained. The chiral symmetric solution of the SD equations is found.

Asymptotic behavior of the effective potential of composite fields in a curved space-time

The asymptotic behavior of the effective action of composite spinor fields in the Yang-Mills theory, interacting with fermions, in a curved space-time, is computed. It is shown that the requirement that the theory be stable in the limit of large curvatures leads to restrictions on the fermionic multiplet contents. The asymptotic behavior of the effective action of composite bosonic fields in quantized R2-gravity with a scalar field is found.

Asymptotic behavior of the effective potential of composite fields in a curved space-time

Asymptotic behavior of the effective potential of composite fields in a curved space-time

Ambiguity in the Effective Potential of Composite Fields

If is argued that there exists an ambiguity in the definition of the effective potential for bilocal composite fields. The ambiguity stems from arbitrariness of adding a polynomial of the source function. Physically meaningful predictions are deduced from the effective potential only when the source function vanishes. The above statement is examined in quantum electrodynamics and the Yukawa theory. A possibility of having a convenient expression of the effective potential is discussed.